Five operations into two

Citation

(1998), "Five operations into two", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 6. https://doi.org/10.1108/aeat.1998.12770fab.009

Five operations into two

Five operations into two

Keywords Aerospace, Geo. Kingsbury MHP, Machining

Three mill-turning centres supplied by Geo. Kingsbury MHP Machines have apparently resulted in significant improvements in productivity only months after installation at Dunlop Equipment, Coventry (Plate 7). On a family of air-oil separator body components, for instance, the machines have consolidated five machining operations into two, saving floor time, speeding turn-round and reducing the risk of handling damage.

Previously, each separator body was initially rough turned inside and out. The component was then transferred to a machining centre for pitch circle drilling of a series of holes in the top. It subsequently went for finish turning and was then sent for anodising after which it was skim turned to remove the anodising in one position.

By contrast, on one of the MHP 50 Series II machines, the component is finish turned and the PCD holes are produced using C-axis control combined with the powered tooling facility. The body is then reversed in the chuck and the inside is bored to a finish, following which it is sent for anodising as before.

Dunlop Equipment manufactures a range of airframe and aero engine-related components for UK and overseas aerospace manufacturers. The company is relatively new, having been set up under the auspices of parent company, BTR, to form part of its aerospace group. Three product modules primarily manufacture bleed valves and air-oil separators; solenoid valves; and helicopter servo-actuators and rudder bias struts. The Coventry site is fully integrated from computer-aided design through to CNC machining capability.

Plate 7 Dunlop Equipment's air-oil separator bodies are now produced in two operations in a Geo. Kingsbury MHP 50 Series II mill-turn centre

Components are manufactured in a wide range of materials in cast and billet form. Stainless steel, aluminium and titanium are routinely processed. Tolerances are better than 25 microns using in-house turning, milling, grinding, lapping and honing facilities. One-off capability is the aim but batch quantities are more commonly up to 20-off.

The company has been a consistent investor in modern CNC machine tools and the three MHP 50 Series II machines were purchased as part of a general expansion of Dunlop Equipment's manufacturing resources. Production engineer Graham Ball explained, "We have an extensive range of products which is sold into OEM and spares applications. The civil aviation sector has been booming lately and meant that we had to step up capacity to meet demand. This investment in mill-turning was to fulfil a requirement for 8-inch chucking lathes capable of turning and integrated second operation work on small to medium-sized components".

The machines were specifically required for the bleed valve and solenoid modules where they have been integrated with existing equipment including other CNC lathes and machining centres. Existing turning capacity was all of 10-inch capacity and it was felt that an 8-inch machine would be useful for much of the smaller work, allowing production to be more evenly distributed.

"We were keen to purchase machines with second operation capability to provide optimum flexibility", remarked Mr Ball. "Even an apparently simple application may involve turning a blank and drilling a timing hole for pallet location on one of our machining centres ­ drilling which would otherwise require a separate operation. At the other extreme it may be possible to finish components with quite complicated cross-holes or PCD requirements in a minimal number of operations, as has proved to be the case".

Factors in favour of the MHP 50 included competitive pricing and speed of delivery compared with alternatives. Additionally, as Geo. Kingsbury MHP is the machine manufacturer, it was possible to combine an element of customisation that would not have been available from an agent or distributor within the same time frame.

"We were keen to keep commonality of operators' program codes with our existing machines so that program transfer and flexible manning would be simplified", Mr Ball recalled. "We also had the tool probe modified to suit our needs and the C-axis control was adjusted so that it could be jogged around. MHP were very helpful with all of this; in fact we had two of our machine operators visit their factory to help develop the specification".

Two machines have a fully programmable tailstock whereas the other is manually set. Otherwise they are identical, each having the benefit of a turret that allows powered tools to be placed in any station. All are supplied with through-tool coolant. Pratt Burnerd quick change chucks are a Dunlop standard. The lathes are employed on a wide range of work with cycle times ranging from 10 to 100 minutes according to complexity. Accuracy is rated as very good.

Operators like the VDI standard tooling which permits tool changes in around one hour, though this may reduce further with a planned move to centralised pre-setting. The graphic simulation facility on the CNC is said to be useful, particularly for new jobs or set-up checks. On the machines with an automatic tailstock ­ destined for use in production of long piston-type components ­ the ease of adjustment and operation is very popular, to the extent that it is coveted by the operators of lathes without this facility.

Mr Ball concluded, "We are very pleased with the performance of these machines and also with the service from Geo. Kingsbury MHP. There is no problem in meeting our tolerance requirements and the lathes have proved very effective in production".

Further details can be obtained from Geo. Kingsbury MHP Machines Ltd. Tel: +44 (0) 1452 520299; Fax: +44 (0) 1452 300087.